I didn't see the Black Panther as I am not a superhero film type person generally, so I thought I hadn't seen this actor, but then realised when watching the news reports about him that I had in fact seen him in the James Brown biopic "Get on up", which although as a film was quite variable in tone, his performance was good.
Sad, and as you say cancer is a bastard. He sounds to have been quite a dignified man from all accounts.